Manufacture of cellulose derivative materials



Patented Apr. 25, 1939 MANUFACTURE OF CELLULOSE DERIVATIVE MATERIALS Henry Dreyfus, London, England No Drawing. Application January 12, 1937, Se-

1 M. 120,221. In Great Britain March '1,

4 Claims.

This invention relates to improvements in the production and treatment of artificial materials, and particularly to improvements in processes wherein artificial filaments, yarns and other ma- 5 terials containing organic derivatives of cellulose are stretched.

It is known that by stretching artificial filaments and similar materials having a basis of organic derivatives of cellulose their physical properties, and particularly their tensile strength, may be improved. It is possible, however, to stretch artificial filaments, yarns and similar textile materials by only a relatively small extent, for example about to when they are in a finished condition, and in order that a higher degree of stretching may be achieved, it is in general necessary to bring the materials to a softened condition, for example by treatment with volatile solvents.

According to the present invention artificial filaments, threads, foils and similar materials of cellulose acetate and other organic derivatives of cellulose which contain plasticisers therefor are stretched in the presence of a hot aqueous 25 fluid, e. g. wet steam or hot water, and in this manner products having improved tenacities may be obtained.

The invention is of particular importance in connection with the manufacture of artificial filaments, yarns and similar textile materials having-a basis of cellulose acetate, but it is also applicable generally to the manufacture of artificial textile materials, foils, films and the like having a basis of organic derivatives of cellulose, for 5 example cellulose formate, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose nitroacetate and other cellulose esters and mixed esters, methyl cellulose, ethyl cellulose, butyl cellulose and other celluose ethers and mixed 40 ethers, and cellulose ether-esters, e. g. ethyl cellulose acetate and oxyethyl cellulose actate.

The plasticisers employed according to the present invention may be plasticisers which are compatible with the cellulose derivatives in only low proportions; for example 510% or 20%. Ex-

amples of such plasticisers are butyl and amyl phthalates, butyl citrate, glyceryl tri-benzoate and triphenyl and tricresyl phosphates. It is preferable, however, that the plasticisers should be compatible in higher proportions, e, g. 50-70% and particularly 100% or more on the weight of the cellulose derivative. this character are dibutyl tartrate, diamyl tartrate, dimethyl phthalate, diethyl phthalate, di-

(methyl glycol) phthalate, di (ethyl glycol) Suitable plasticisers of phthalate, triethyl citrate, cresyl glyceryl diacetate, methyl 'cyclohexanyl oralate, benzyl benzoate, benzyl alcohol, triacetin, triphenyl-acetin and aromatic sulphon-amides and alkyl substitution derivatives thereof, e. g. para-toluene sulphon-amide and the isomeric xylene sulphonamides. Mixtures of plasticisers, e. g.. mixtures containing plasticisers of low and high compatibility, may be employed.

The plasticisers may be incorporated in artificial yarns and othermaterials by introducing them into the cellulose derivative solutions and forming the solutions into the artificial materials by the evaporative process. Wet coagulation processes may also, if desired, be employed. When materials are formed by wet processes from solutions containing plasticisers, the coagulating conditions should be such that the required proportion of plasticiser remains in the materials after they have been withdrawn from the coagulating bath. The plasticisers may also be incorporated in artificial materials by treating them after their formation with a medium containing a plasticiser. For example yarns, hanked or on bobbins, preferably bobbins which have an open wind, may be immersed in a solution or emulsion of the plasticiser, either in water or in a suitable organic liquid, for example benzene,-

ether or carbon tetrachloride. For example hanks of cellulose acetate yarn may be immersed in an emulsion of dimethyl phthalate in water until they have taken up the desired amount of plasticiser.

The plasticisers may be present in the materials to be stretched in substantial-proportions, e, g. in proportions of 40-60% up to or more, based on the weight of the cellulose derivative, or in smaller proportions, e. g. 2 or 5-10% or 20%. In general the higher the proportion of plasticiser present, the lower may be the temperature of the steam or hot water to obtain any desired degree of stretch. I

Artificial filaments, yarns and similar textile materials may be stretched in the form of banks, but preferably materials are stretched during the course of their travel from one point to another, for example during the transferof yarns from one bobbin to another. It is of particular advantage to stretch a plurality of yarns simultaneously whilst they are spaced apart in parallel alignment and substantially in sheet formation, by means of devices stretching across the entire sheet. Again, artificial filaments and like materials may be stretched during their travel from spinning machines in which they have been produring which the materials are released from the way:-

stretching tension.

Stretching of the materials may be carried out in the presence of steam, preferably wet steam, or hotwater at any suitable temperature, for example to ,C. or higher temperatures, for example .115 to C. or more. Details with regard to the stretching operations are given in U. 8. applications S. Nos. 4,510, filed February 1st, 1935, 4,511, filed February 1st, 1935, 69,282, filed March 17, 1936, and 17,242, filed April 19th, 1935 to which reference is made in this connection. The degree of stretch may be relatively low, for example 50, or 250% of the original length of the materials, or considerably higher degrees of stretch may be effected up to 1000% or even more of the original length of the materials.

The plasticisers or a proportion thereof may be removed from the filaments or other materials during or after the stretching operation, and it is preferable that this should be done in the case oftextile materials which contain high proportions of plasticisers, e. g. 60% or more. Thus when stretching is eifected by passing textile materials containing water-soluble plasticisers through hot water some or all of the plasticiser may be dissolved out. Again, the plasticisers may be wholly or partly removed from the materials after the stretching operation by any suitable method, e. g. by treating the materials with a liquid which is a solvent for the plasticiser employed and is a non-solvent for the organic derivative of cellulose. Examples of suitable liquids are hydrocarbons and chlorinated hydrocarbons, e. g. benzene, toluene, dichlorethylene, and carbon tetrachloride, ethers, e. g. diethyl ether and di-isopropyl ether, and alcohols, e. g. methyl alcohol and ethyl alcohol. Water or aqueous solutions of suitable liquids, e. g. aqueous solutions of alcohols, may also be employed.

The following examples illustrate the invention but are not to be regarded as limiting it in any Eicample 1 Yarns of cellulose acetate containing dibutyl tartrate in a proportion of about 70% of the weight of the cellulose acetate are led from a creel of bobbins and passed through a reed in warp formation. Whilst in this formation the yarns are led through a vessel containing water at a temperature of 90-100 C. and are simultaneously stretched. Dibutyl tartrate remaining in the materials after the stretching operation is removed therefrom by treatment with a hydrocarbon solvent.

Example 2 in part, by treatment of the materials with ethyl alcohol.

' Example 3 Cellulose acetate yarn containing 5% of its weight of diethyl phthalate is stretched while passing through a chamber containing wet steam at a temperature of about 112 C.

Example 4 Cellulose acetate yam containing about 10% of its weight of triacetin is stretched while passing through a chamber containing wet steam at a temperature of 108 C.

Example 5 Having described my invention, what. I desire to secure by Letters Patent is:

1. Process for increasing the tensile strength of artificial materials, which comprises stretching by at least 50% of their original length in a hot aqueous fluid which is at a temperature above 100 C., which is free from organic softening agents and which is selected from the group consisting of wet steam and hot water, artificial filaments, foils and similar materials made of organic derivatives of cellulose and containing plasticizers which are compatible with the cellulose derivatives in a proportion of at least 50%.

2. Process for increasing the tensile strength of artificial materials, which comprises stretching by at least 50% of their original length in a hot aqueous fluid which is at a. temperature above 100 C., which is free from organic softening agents and which is selected from the group consisting of wet steamand hot water, artificial filaments, foils and similar materials made of organic derivatives of cellulose and containing plasticizers which are compatible with the cel-.

lulose derivatives in a proportion of at least 50%,

the plasticizers being present in the materials in a proportion of from 2 to 20% of their weight.

3. Process for increasing the tensile strength of artificial materials, which comprises stretching by at least 50% of their original length in a hot aqueous fluid which is at a temperature above 100 C., which is free from organic softening agents and which is selected from the group consisting of wet steam and hot water, artificial filaments, foils and similar materials made of cellulose acetate and containing plasticizers which are compatible with the cellulose acetate in a proportion of at least 50%.

4. Process for increasing the tensile strength of artificial materials, which comprises stretching by at least 50% of their original length in,

a hot aqueous fluid which is at a temperature above 10010., which is free from organic softening agents-and which is selected from the group consisting of wet steam and hot water, artificial filaments, foils and similar materials made of cellulose acetate and containing plasticizers which are compatible with the cellulose acetate in a proportion of at least 50%, the plasticizers being present in the materials in a proportion of from 2 to 20% of their weight.

HENRY DREYFUS.

CERTIFICATE OF CORRECTION Patent No. 2,'155,L;11. April 25,19 9.

' I HENRY DREYFUS;

It is hereby certified that error appears in the printed specification oi the-above numbered patent requiring correction as follows: Page Leec- 0nd column, line 2, for f'oraiate" read oxalate; and that the said Letters Patent shouldbe read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 13th day of June, A. D. 1959.

Henry Van Ars'dale (Seal) Acting Commissioner of Patents. 

